I was mid-flat white at my local cafe when I overheard a parent-to-parent conversation at the next table about schools in the area. “It’s a very good school,” said Mum One to Mum Two, “It’s a decile 10.”

I was tempted to push the boundaries of social etiquette and jump in and ask Mum One to qualify what she meant by “very good”. Very good achievement outcomes on the National Standards rankings? Very good e-learning initiatives? Very good opportunities for sporting and cultural activities? Very good swimming pools at her child’s friends’ houses??

It is unfair to be so flippant. High decile schools often – but not always – boast high performance to back up such logic. There has long been a correlation between student academic achievement and socio-economic status. However, it seems parents are being too quick to make the connection between high deciles and high achievement.

This certainly appears to be the thinking driving the Education Review Office’s (ERO) decision this year to scrap decile ratings from its school reports.

Dr Graham Stoop, ERO’s chief executive, says the decision was made in an effort to “correct the stereotype that a school’s decile equals performance”. The Ministry of Education supports ERO’s stance.

“Too often, it is seen as a rating of the quality of the education that a school provides, and this is simply not correct,” said Stoop, following the announcement. Stoop says there are high decile schools in New Zealand that are underperforming and low decile schools that are outstanding.

While those in education circles understand what a school decile is – a rating of one to 10 that reflects the socio-economic background of its students – many parents appear to confuse this rating with the quality of the education delivered at that school. There have been suggestions of “white flight”, with Ministry of Education data showing that 60,000 Pākehā children attended low decile schools in 2002, falling to half that number in 2010.

Christopher Lubienski, in his article The Decile Delusion says that schools are aware of this conflation, and many play on it in their marketing. As one principal stated: [His school’s high decile] “is a great marketing tool. Parents think that it is a measure of school quality. They don’t understand what it measures. It is a blunt instrument”. Consequently, this principal and many others use their schools’ decile ranking as a marketing device to (mis)represent the school to parents.

Obviously, the better the decile, the better positioned schools are to gain from any confusion on the matter. Lubienski’s research found that lower decile schools tend not to note their decile ranking on their homepage. Higher deciles have a much greater tendency to trumpet their rankings, “even though it provides parents with virtually no direct information about the quality of education at the school. Instead, it apparently tells parents about the ‘quality’ of their child’s potential peers at a given school.”

It is rational to expect school leaders to promote higher decile ratings if it will help their school, but Lubienski says these patterns also suggest a systemic perversion of the purpose of the decile system, which is designed to offer advantages to schools serving poorer kids but has apparently been turned into a marketable indicator of affluence.

In Stoop’s Herald editorial, he said ERO’s decision to remove decile ratings was “applauded by principals the length and breadth of New Zealand”, suggesting schools are eager for the public misconception around deciles to end.

Ironcially, a lower decile rating should indicate to parents that the school receives considerably more funding per student from the Government than those at a higher decile school.

The Ministry of Education says the increased funding given to lower decile schools is to provide additional resources to support their students’ learning needs. The lower a school’s decile rating, the more funding it gets.

The principal of a new school I visited recently told me she suspected its decile ranking was lower than it should be. Although a crude and inaccurate measure, the standard of the houses and cars surrounding the school would suggest she is correct. “But don’t write that,” she hastened to add, “We don’t want them to change it because then we’ll get less funding!”

However, despite the higher funding for low decile schools, it appears higher decile schools are still likely to achieve more revenue per students. From its survey of five decile 1 and five decile 10 Auckland schools, ital Education Aotearoa***found that the extra funding received by low decile schools was insufficient to bridge the gap by what one principal described as “the fundraising economy” of high decile schools. According to its findings, a high decile Auckland school can ask a child’s parents for $600 at the start of the year, as a donation and “activity fees”, and expect a 90 per cent response rate from parents, whereas a low decile school might ask for $10 a term, and get a 30-35 per cent response rate.

Principals at low decile schools said the needs of their students, who regularly start school two years behind “normal” levels, were immediate and overwhelming, leaving little time for fundraising, which in high decile schools tends to be the domain of the “power mums”. The survey showed that when all income streams were considered, the decile 10 schools brought in $8653 on average per pupil, compared with $7518 per pupil at the decile 1 schools.

One of the main criticisms ERO has faced for removing the decile information from its reports is that they appear to be hiding information from the public.

However, as Stoop points out, anyone can easily find the decile rating of a school online. The Ministry still makes this information publicly available. It is not about eliminating the deciles, more about removing their significance in schools’ ERO reports.

Those commenting online tend to agree. “Anyone with half a brain can figure out where the decile 1 schools are – nowhere near the decile 10 ones; no one’s trying to dupe you into sending your precocious pre-teen to Manurewa Primary,” says one respondent. “A decile 1 school might well outperform a decile 3 school, yet parents shun it for its decile rating. The underlying message is that parents should be looking a little harder. Heaven forbid you call the school or look at their website instead of picking a decile number.”

Stoop agrees that deciles do not necessarily contextualise a school. In his editorial, he gives the example of a decile 5 primary school with a mix of students from professional families in a high socio-economic bracket and students from new immigrant families. Nearby is another decile 5 school with a more homogenous profile. In addition to different socioeconomic profiles, the achievement profiles are also very different.

It seems a number is insufficient to illustrate the intricacies of a school’s socioeconomic profile. Yet, people agree this information should be available.

New Zealand Educational Institute believes clear information about the social and economic context of schools should be published in place of decile ratings. Data on student transience, the number of children with special needs or English as a second language, and the number of children attending breakfast clubs would potentially be more use than a mere number.